Pulse equalizer



B. sMALLl-:R 2,636,118 PULSE EQUALIZER 5 Sheets-Sheet l April 21, 1953 Filed Feb. 28. 1952 B. SMALLER PULSE EQUALIZER April 21, 1953 5 Sheets-Sheet 2 Filed Feb. 28. 1952 V INVENTOR. .5er/4wd @Haller FIIEE B. SMALLER PULSE EQUALIZER April 21, 1953 5 Sheets--SheeiI 5 Filed Feb. 28. 1952 ,MITP

l v--u INVENTOR Ycoincidence counting Patented Apr. 21, 1953 UNITED STATES PATENT OFFICE PULSE EQUALIZER ABernard I'Smaller, Chicago, Ill., assignorto `the United States of America as .representedgbytthe :United States Atomic Energy `Commission ApplicationFebruary 28, 1952,Seria1No.273,905

(Cl. Z50-427) 12 Claims.

L'The presentinvention relates to devices for equalizing 'pulses of different-amplitudes, Vand more `specifically to devices for counting pulse coincidences from differentV sources.

Inv the (past, many `devices `have been used to transform pulses vof `random amplitudes into pulses of .equal amplitudes. One well known deviceiforaccomplishing this purpose is the multivibrator which produces a pulse with -a` predetermined` amplitude for each input pulse irrespective of the amplitude of the inputpulse, provided thatall of the `input pulses are of sufficient amplitudeto trigger the multivibrator. However,

suchf circuits `are triggered when the incoming ipulses reach a threshold amplitude. Since the time required -for a pulse to reach fthis threshold value isaifunctionfofthe amplitude of the pulse, pulses offdiiierent amplitudes will not be triggered .at the ridentical time lapse after the pulse i is impressed `upon the multivibrator.

`amplitude Willfcause the coincidence Vcounter to fail to record some .coincidences of` pulses.

Itis an object of the present invention to providea device for transforming pulses ci random yamplitudes tinto"pulses "of equal .amplitude in which thedelay timeior all pulsesis essentially constant.

Z'Itiis also an object of .thepresentinventionto -provide devices for counting the .coincidences of pulses, even when ,the pulses are of diierent amplitudes.

Further Objects andadvantages of the-present invention will become readily apparent to the man .skilled inthe art from a `further reading `of thepresent specification and claimsJ4 particularly -when viewed Ain the light of the drawings, in Ywhich:

.Figure `1 .is a schematic block 'diagram :of .a device i illustrating the teachings ofv the` present invention;

Figure 2 is afschematic electrical circuit diagram .of vonefof the .two incoming pulse channels;

Figurei is a schematic electrical circuit-diagram ofia concidencemixenintegratcrand discriminaton `;.and output i multivibrator, such n as v illustratedlin theeorresponding blocks of Figure l;

.Figure 4 is an` illustrativegraph .showing .the shape of the electrical pulses generated in differ- "This fact has been .illustrated Where appropriate 2 ent portions ofthe -circu'it bya typical'sgna pulse;

Figure?, is aggraph showing typical-pulsesgen- `erated luy-'signal pulses at the output of lthe -integrating circuit; and

`Figure 6 `is agraph of a typical electrical pulse developed at the output of .one of the incoming channels from a signal pulse.

The present invention -may` be used tocount thecoincidences of pulses lgenerated by `any two signal pulse sources, such as the pulsesfemerging from counters, ionization chambers, orscintillation counters.

The signal pulsesgeneratedby-each` of thewtwo pulse sources are Aconducted to a coincidence mixer lthrough-:separate channels 12. and-Hl. While the `present -circuit has been fdesignedwto count the coincidences of pulses fro-mvtwo` pulse sources, it will be clear to the manskilled inthe art that the circuit could be readily modified to `count'the coincidences of pulses from any inumberof .pulsesourcea anadditional pulse channel being `used `.with an additional coincidencemixer for each additional pulsesource.

Each of the pulse `channels I2 and :M cornprises a `delay line circuit IE, an integratingf'cir- `cuit i8, a` pedestal multivibratorZU, and Y.a difference-amplifier 22.

The method of obtaining pulses of equal: amplitude and uniform delay time vfrom random `amvplitude pulses maybe explained Withureference to 'Figures 1, 4,5V and 6. Ifit isfassumedthat a `negative signal pulse is impressed` upon the ,pulse `channel I2 or .I4 .With approximately the shape i shown at 24 Figure 4, the delay line lcircuit 'i6 will delayzthe .pulse for a predetermined `period of` time,V `for example one-half zmicrosecond, to

.formthe pulse illustrated at'26 Ain Figure 4.

:'It will he noted thatutheamplitudesyofhoth pulses124 'and126'willinot be constant, but will be between` upper andyzlovver` limits, inpgeneral.

intall of the iigures by showing the upper .and lower 'limitsiin solid lines and shading the area betvveen the solid lines.

At the same time that the delay line circuit I6 isdelayingthe'signal pulse, the integrating circut I8^will convertthesignal pulse toA a -pulse `of a long duration shown at 28 in Figure 5. This equals the amplitude of the delayed pulse .261e- .sulting .fromthesame .Signal pulse. The delayed pulses 26 andthe integrated pulses 28 are imythrough a cathode resistor 6|).

pressed upon the input of the difference amplifier 22. The pedestal multivibrator 26 also generates a negative pulse 30 which is algebraically added to the pulses 26 and 28 at the input of the difference amplifier 22. It is to be noted, that even though all three pulses 26, 28 and 30 which are impressed upon the diierence amplifier 22 are negative, the effect of the integrated pulse 28 upon the output of the difference amplifier 22 is to oppose the other two pulses 26 and 36.

The purpose of the pedestal pulses 36 is to provide the pulses resulting from the difference of the delayed pulses 26 and the integrated pulses 28 with sufficiently positive amplitude to permit the coincidence mixer I6 to operate eiciently, however, the pedestal pulses 36 do not contribute to the uniform amplitudes of the pulses emerging from each channel, or to the uniform delay time, except insofar as they are maintained at a constant amplitude.

The three pulses 26, 28 and 36 which are generated from each signal pulse are merged into a single pulse 32 appearing in the output of the differenceY amplifier 22, shown in Figure 6. It will be noted, that the apex of the pulse 26 appears in the pulse 32 at the point 34, and that this point 34 is `a point of uniform time delay and constant amplitude for all signal pulses. The amplitude of the point 34 is equal to the amplitude of the pedestal pulse 36, since the delayed pulse 26 and integrated pulse 28 cancel each other at this point. Also, the delay time for all pulses 32 will be substantially uniform, since only a Very small proportion of the apex of each signal pulse 24 is used for purposes of triggering circuits due to the fact that the amplitude of the point 34 on each pulse 32, regardless of the amplitude of the signal pulse, will be equal to that of the pedestal pulses 30.

Figure 2 shows a schematic circuit diagram of the circuits which constitute one of the channels I2 or I4. An input connector 4|] is adapted to be connected to one of the two sources of signal pulses whose coincidences are to be counted. One terminal of the input connector 4|] is connected to the inputs of the delay line circuit I6, the integrating circuit I8 and the pedestal multivibrator 20, and the other terminal of the input connector 48 is connected to the common reference, or ground, circuit 58.

The delay line circuit I6 consists of a cathode follower amplifier 42 and a delay line 44. The cathode follower amplifier has a vacuum tube 46 with a plate 48 connected directly to the positive terminal of a source of power, such as battery 56. Vacuum tube 46 also has a grid 52 and a cathode 54, the grid 52 being connected to one terminal of the input connector 46 through a condenser 56, and the cathode 54 being connected to the other terminal of input connector 46 A grid bias resistor 62 is connected between the grid 52 and the ground circuit 58. The delay line 44 is coupled to the cathode 54 through a coupling condenser 64. The delay line 44 is constructed to provide a one-half microsecond delay for all pulses, and the cathode follower 42 provides a high impedance to low impedance coupling beiween the input connector 48 and the delay line The integrating circuit I8 is also connected to the input connector 40 in the same manner as the delay line circuit I6, and includes a condenser '|2, resistor 14, and crystal rectifier 'I6 connected in series to pass only negative charges from the input connector 40 to the diierence amplifier 22. A resistor 86 and a condenser 18 are connected in parallel between the ground circuit 58 and the output side of the crystal rectifier i6, and a second crystal rectifier 82 is connected to pass positive charges from the junction between the resistor 14 and the crystal rectifier 'I6 to the ground circuit 58.

The pedestal multivibrator 20 comprises a cathode follower 98 and a multivibrator |60. The cathode follower 88 uses a vacuum tube |02 having a grid |64 connected to the input connector 46 through a crystal rectifier |06 and a coupling condenser |68. A grid lbias resistor ||0 connects the grid |64 to the ground circuit 58. Vacuum tube |62 also includes a plate ||2 directly connected to the positive terminal of battery 58, and a cathode II4 connected to the ground circuit 56 through a cathode resistor I6.

The multivibrator |66 includes a pair of vacuum tubes H8 and |20. Vacuum tube ||8 has a grid |22 connected to the cathode ||4 of vacuum tube |62 through a coupling condenser |24. The grid |22 of vacuum tube |I8 is also connected to the ground circuit 58 through a grid resistor |26, and to the positive terminal of battery 56 through the series connected potentiometer |26 and resistor |36. Vacuum tube ||8 is also provided with a plate |32 and a cathode |34, the plate |32 being connected to the positive terminal of battery 56 through a plate resistor |66, and the cathode |34 being connected to the ground circuit 58 through a cathode resistor |38. Vacuum tube |20 is provided with a grid |48 coupled to the plate |32 of the vacuum tube |58 through a condenser |42. The grid |40 of vacuum tube |26 is also connected to the ground circuit through a grid bias resistor |44. Vacuum tube |20 has a plate |46 and a cathode |48, the cathode |48 being directly connected to the cathode |34 of Vacuum tube H8, and the plate I 46 being connected to the positive terminal of battery 58 through a plate resistor |56.

The difference amplifier 22 has a cathode follower using a vacuum tube 66 and an ampliiier using a vacuum tube |52. Vacuum tube 66 is provided with a grid 66 which is coupled to the crystal rectifier 'i6 of the integrating circuit I8 through a condenser 10; and a plate 84 directly connected to the positive terminal of battery 58. A positive bias is placed upon the grid 68 of vacuum tube 66 by means of a voltage divider Yconnected across the terminals of battery 5l), the

voltage divider consisting of series connected resistors 86 and 92 connected between the positive terminal of battery 50 and the grid 68, and parallel connected condenser 94 and resistor 66 connected between the ground circuit 58 andthe junction between resistors 86 and 92. Vacuum tube 66 is also provided with a cathode 86 which is connected to the ground circuit 58 through a resistor 88. Vacuum tube |52 has a cathode |54 directly connected to the cathode 86 of vacuum tube 66. Vacuum tube |52 is also provided with a positively biased grid |56 which is connected through resistor |60 to the junction point between resistors 98 and 92. The grid |56 is also connected to the plate |46 of vacuum tube I 26 of the pedestal multivibrator 20 through series connected coupling condenser |16 and resistor |12, The grid |56 is also coupled to the output of the delay line circuit I6 through a coupling condenserA |68 and a voltage dividing network consisting of resistor |66 and rheostat |64 connected between the delayline 44 and the ground 15 circuit 58. t Vacuum-`-tube |52 .ist also; provided fwithea-plate :|58 which :isiconneoted yto f the posit -tivet-lterminal Vof battery-@50 .-throughia` `platev resistor M52.

fiIhe` operation` :of the` :wave shaping .rcircuits `'shownfin` Figurefzsmaymowibe described. :A negative signal,pulserffromtsaxpulseir source1.is,;im pressed upon the grids 52 `of vacuum .tubetj |64 `of vacuumttube m2, and upon the integrating` circuit |8. Thescathodecfollower exofrtheipedestal i1multivibrator2immediatelyconductsthe negativefpulse to the` multivibrator l I tu n causing lvac- .uum ktube |20 `torbecome .conducting and :placing na negativetpulse (pulse Slisliown"in'lFigureiD` 'on ,the'grid 1| 56 of `vacuumLtube `1| 52 I inthe difference `ampliiier 22. VAt :thesame time; theinegativefsignal `:pulseis :integrated .lbyt `the 'integrating-circuit fcl 8 andi conductedxtolthe gridsl roflithe difference fiamplicrxn. As ia result, a `:negative integrated rzpjulse 2 8' rtligureA 5r appearssuponltheicathode 85 ".ofvacuum tubert .andralso uponl-the cathode l 54 `of vacuumtube |1521of5the diiierence :amplifierl lI'hispulsein effect drives-the grid i156 i of vacuum .tube L|52zmore positive. 'The cathode follower 't2 coi '.the :delay linezcircuit t immediately-J conducts the negative signal pulse from rconnector-Mi -to Athe` delay line 1M ywhereiit isA retarded by approxi- Imately one-:half `microsecond, this puise -being :illustrated as pulselZEfin Figure 4. This pulse remainsnnegative Lin polarity, `and is `impressed upon )the grid`if|56 `of"vacuum tube |52 'oflthe ldierencefamplier 22 to 'opposethe pulsefifrom .'.thefintegrating circuit` il` resultingfronithe same Lsignalpulse. Pulse-tti `from the `pedestal multi- 1 "vibratorli adds 1to1 the delayed-1` pulse2 `-In this f 'mannenlpulses L2 6,1222 `andtil,illustrated in Figiures. 4 tand f 53 are impressed upon the `dink-)rence Sampliii'er L22 resulting in =pulse`-'`32 ,i shown in 1Fig- :ure 6, which A appears Lupon the plate -`i et or racuum tube |52rof the difference amplifier 22.

In? fone particular construction embodying' the 1. present invention, L-onefsecton cfa 4type 12AUY Nvacuum-tube was-used for Vacuum tube ofthe i idelay line-circuit 6, and! the other section of the type `12AU7 '-vacuumritubewas -used for vacuum l' tube |l||2 Softthe imultivibrator pedestal circuit 2Q. 11n like f manner, type. 12AU'7 vacuum tubes -were .u'sedior vacuumftubes't and F52, and'wacuum l tubes l|i| 8il and 't2 D. :Battery delivered 250volts ohm delay lineia'daptedto provideardelayiof `microsecond. The grid `|22 of vacuum tube H8 #of `lthe pedestal -multivibrator- 2t "was Vpositively t biased l2 volts` with respect'to thefground'circuit SBV-andfthefcathode `|34 `was biased a `positive l5 tvoltslwith respect 'to fthe lground circuit 58. The .'crystal. 'rectiers 1 llt, 82, and -t iwere -all `type '11`N34 crystalL'rectifiers "The `'grids 68 and 156 rvof @vacuum tubes 65 and``|52in the-difference amplifier 22 were biased a positive 17 volts, while the f cathodes-i and le!! of these tubes werepositively Aibiasedi-Q()"volts-withrespect to the ground cirrcuit'58.

statedj-'the-outputs vironvthe "diiierence `amplifiers 22in each'ofthe pulse channels l2 and Mare impressed upon the coincidence mixer |ii. The-coincidence mixer ll is shown inidetail `in VFigure 3, and'includes a `vacuum tube "llt ofthe gated beamtype. A first controlgrid |16 `is coupled totheiplate tot of the difference amplifiier`f22 ofchannel |4 througha coupling condenser |13, while a second controljgrid I'SG is t coupled similarly tothe difference ampliier22cf `A`channel' |2 through a coupling condenser |82. "`Therrst'control `grid |76. is connected to 'the alsoshasfan accelerator t2 6|) connectedto thejuncftion between the,pla.te iresistor f| 96 :fand :thefvoltage dropping resistor 'wir through :series `con- `nectedresistors 2|l2 fand '2.64,'Lthe :j unction: between J resistors `2|22 andfi2|l4 irbeing wbr-.passed @to` the `ground circuit I 58; throughxa `doy-pass ffcondenser uum tube' H4 .has aezlcathode 2i|2 c'onnectedzto :ground ithrough `condenser 2 4 'andresiston 21| 6,

thecathode I2` 2 alsof being connected ,to the junction between the'rplateresistor tt rand thevoltage `dropping resistor 'byiresistor 2 It.

The 'output of vthez coincidence'smixer circuit il .isimpressed upon the input of the integrator-'and discriminator .circuita'f22li. .1 The integrator `and discriminator Acircuiti 22 incorporates atvacuum tube 22 2` having a grid 224 coupled rtothe plate 92 "of lvacuum` tube |14. oflthe coincidence mixer circuit It through a couplingcondenserx226and a crystal rectiii'er228. lVacuumft'ube22223 hasa plate 22er connected fto' ith'e. `positive terminal of battery |34 through voltagefdroppingresistor 98, and a cathode 232 Vconnected to `theigroundcircuit 58 `through a cathoderesistor 234. 'Tliergrid 224 is also connected to: theV ground circuit-58 through a resistor 226. 'Thetoutput from the integrator and discriminator circuit 226 is-taken from the cathode 2321ervacuumtube'222 through a `pair of series connected" resistors"-"2f38 and'24`i). The resistors-238- and li are shunted bya` crystal Vrectiiierl'lZ connected to pass negative charges from the cathode 232, and the ljunctionfbetween the two resistors 233 and `24|) is by-passed to the ground circuit E3 by a condenser244. 1A\11'e'sistor 245 is connected between the groundv circuit-5B and the junction of resistor' 2461 andcrystalrectifier 242. A condenser 246 is -connected between the plate 230 of vacuum tubel222 andthe ground circuitr58.

The output from the integratorland-discriminator circuit 225i is impressed upon the input of the multivibrator circuit-243. The-multivibrator circuit `248 uses vacuumrtubesl` 25e and 252 connected in a conventional multivibrator "circuit, and hencethis circuit has not been'described in detail. The output of the-multivibrator-circuit 248iis taken from a plate-254 of'vacuurn tube 252,

and is in the formrof anegativelpulse suitable for counting purposes. An outputconnector 256-is coupled to the -platef25ll, and is` adapted to be connected toa pulse counter.

Vacuum tube |14 of the coincidence mixer I0 -is normally essentially non-conducting, and `will become conducting only when positivepulses are impressed upon both ofV the `controlfgridsfllt and at the same time. Ira ipositivepulse is impressed upon only one of theselcontrnl` grids I-'Iti` or |82, vacuum tube |74 will remaineseentially non-conducting regardless `offthe amplitude of the pulse. Hence, the pulses `emerging from `the coincidence mixer circuit .may be counted and represent theoccurrencesofrpulses from the two pulse sources` during thetsame interval of time.

The pulses appearing upon theilplate` k[92.01'

vacuum tube |14 could be counted directly by the multivibrator 248, particularly when relatively large pulses are being used throughout the circuit. However, when it is desired to record the coincidences between pulses of relatively small amplitude, the greatest sensitivity is obtained in the coincidence mixer circuit I9 when a small amount of plate current hows through vacuum tube |14 at all times. Under these conditions, the occurrence of a pulse upon only one of the control grids |16 or |80 of vacuum tube |14 will produce a small pulse on the plate |92 of vacuum tube |14. Hence, it will be necessary to distinguish between the pulses developed upon the plate |92 of vacuum tube |14 which are the result of 'a pulse appearing upon only one of the two control grids |16 or |80 and those which are the result of pulses appearing upon both of the control grids |16 and |89. The integrator and discriminator circuit 229 is for this purpose.

Since it is not necessary to operate with pulses of short time duration, condenser 226, crystal rectiiier 228, and resistor 23B integrate the pulses appearing in the output of the coincidence mixer circuit I and impress these relatively long negative pulses upon the grid 224 of vacuum tube 222. Both the larger and the smaller pulses coming from the coincidence mixer circuit l2 appear as negative pulses upon the cathode 232 Vof vacuum tube 222, and from this point the larger pulses are discriminated from the smaller pulses. Vacuum tube 222 is continuously conducting, thereby establishing a positive bias on the cathode 232 as a result of current iiowing through resistor 234 and resistors 238, 240 and 245. The junction point between resistor 240, crystal rectier 242 and resistor 245 thus assumes a potential positive with respect to the ground circuit 58 and negative with respect to the cathode 232. A negative pulse appearing at the cathode 232 of vacuum tube 222 will only pass through the crystal rectifier 242 if it is of greater magnitude than the diierence in the potential appearing on opposite sides of the crystal rectier 242, since it must travel to a point of lower positive potential. As a result, all pulses of a lesser magnitude than the potential across crystal rectier 242 will leak through the cathode resistor 234 to the ground circuit 5S, since the resistance of resistor 234 will be much less than the sum of resistors 238, 240

and 245. In this manner, only the larger negative pulses will be transmited to the multivibrator circuit 248.

In one embodiment of the present invention, the coincidence mixer circuit l0 made use of a type 6BN5 vacuum tube for vacuum tube |14. The cathode 2 |2 of vacuum tube |14 Was biased between 5.4 and 8.3 volts positive, and the accelerator 200 received a positive potential of approximately 40 volts. Battery |94 delivered 250 volts potential to the circuit. Crystal rectiers |86, |90, 228 and 242 were type 1N34 crystal rectiers. The integrator and discriminator circuit used 1 section of a type 12AU7 vacuum tube for vacuum tube 222. The cathode resistor 234, resistor 238 and resistor 240 were 5100 ohms, and resistor 245 was 51,000 ohms. With these values, the cathode 232 received a positive bias of approximately 1l volts and the junction point of resistor 240, resistor 245 and crystal rectier 242 received a positive potential of approximately 9 volts. The circuit would thus discriminate against all pulses which were not more than 2 volts negative.

The foregoing description of one embodiment of the present invention has been specific and will suggest many other embodiments tothe man skilled in the art. For this reason, it is intended that the scope of the present invention be not limited by the foregoing description thereof, but only by the appended claims.

What is claimed is:

1. A device for measuring the coincidences of electrical pulses from diferent sources comprising, in combination, a channel for each source of electrical pulses, each channel having means to delay a pulse, means to integrate a pulse, and means to subtract the pulse delayed from the pulse integrated, and means for counting the coincidences of pulses connected to the channels.

2. A device for measuring the coincidences of electrical pulses from diierent sources comprising, in combination, a channel for each source, each channel having means to delay a pulse, means to integrate a pulse, means to subtract the pulse delayed from the pulse integrated, and means to algebraically add a pedestal pulse to the difference of said integrated and delayed pulses, and means for counting the coincidences of pulses connected to the channels.

3. A device for measuring the coincidences of electrical pulses from diierent sources comprising, in combination, a channel for each source of pulses, each channel having means to delay a pulse, means to integrate a pulse, and means to subtract the pulse delayed from the pulse integrated, a coincidence mixer connected to each pair of pulse channels, a discriminator circuit connected to the output of the coincidence mixer for discriminating against pulses having amplitudes less than a threshold value, and a counter connected to the output of the discriminator circuit for counting pulses having greater amplitudes than the threshold value.

4. A device for measuring the coincidences of electrical pulses from two sources comprising, in combination, two input channels, each channel having means to delay a pulse, means to integrate a pulse, means to subtract the pulse delayed from the pulse integrated, and means to algebraically add a pedestal pulse to the difference pulse from the integrated and delayed pulses, a coincidence mixer connected to the output of said channels, and a pulse counter connected to the output of the coincidence mixer.

5. A device for measuring the coincidences of electrical pulses from two sources comprising the elements of claim 4 in combination With a discriminator circuit connected between the coincidence mixer and the counter, said discriminator discriminating against pulses having amplitudes lower than a threshold value and conducting pulses having greates amplitudes to the counter.

6. A device for measuring the coincidences of electrical pulses from a plurality of pulse sources comprising, in combination, a channel for each source, each channel having a delay line adapted to be connected to a pulse source, an integrating circuit adapted to be connected to the same pulse source, a difference amplifier having inputs connected to the output of the delay line and integrating circuit, a coincidence mixer connected to the outputs of the diierence amplifiers of the channels, and a counter connected to the output of the coincidence mixer.

'1. A device for measuring the coincidences of electrical pulses from a plurality of pulse sources comprising, in combination, a channel for each source, each channel having a delay line adapted to be connected to a pulse source, an integrating circuit adapted to be connected to the same pulse source, a multivibrator adapted to be connected to the same pulse source, and a difference amplier having inputs connected to the output of the delay line, integrating circuit, and multivibrator, said amplier subtracting the delayed pulse from the integrated pulse, a coincidence mixer connected to the outputs of each pair of channels, and a counter connected to the output of each coincidence mixer.

8. A device for measuring the coincidences of electrical pulses from a plurality of pulse sources comprising the elements of claim 7 in combination with a discriminator connected between each coincidence mixer and the following counter, said discriminator discriminating against pulses having amplitudes smaller than a threshold value.

9. A device for measuring the coincidences of electrical pulses from a plurality of pulse sources comprising the elements of claim 8, wherein each channel is provided with a cathode follower having an input adapted to be connected to a source of pulses and an output connected to the delay line, and a second cathode follower having an input adapted to be connected to the same source of pulses and an output connected to the multivibrator.

10. A device for measuring the coincidences of electrical pulses from different sources comprising, in combination, a channel for each source of pulses, each channel having means to delay a pulse, means to iintegrate a pulse and means to subtract the pulse delayed from the pulse integrated, a coincidence mixer having inputs connected to the outputs of each pair of channels,

an integrator and discriminator connected to the output of at least one coincidence mixer, said integrator and discriminator comprising a vacuum tube having a plate, grid, and cathode, the plate of said vacuum tube being directly connected to a source of voltage, the grid of said vacuum tube being connected to the output of the coincidence mixer through an integrating circuit, and the cathode of said vacuum tube being connected to the negative terminal of the source of voltage through two parallel paths, one of said paths comprising a single resistor, and the other of said paths comprising at least two resistors and a crystal rectifier, said crystal rectifier being connected between the cathode and the junction point between the two resistors in said second path and connected to pass positive charges to the cathode, and a counter connected to the junction point of the crystal rectifier and the two resistors in said second path.

1l. A device for transforming pulses of random amplitudes to pulses of equal amplitude comprising means to delay the pulses, means to integrate the pulses, and means to subject the pulses delayed from the pulses integrated.

12. A device for transforming pulses of random amplitudes to pulses of equal amplitudes comprising, in combination, means to delay a pulse, means to integrate a pulse, means to subtract the pulse delayed from the pulse integrated, and means to algebraically add a pedestal pulse to the difference between the integrated and delayed pulses.

BERNARD SMALLER.

No references cited, 

